title: Decolorization of methylene blue in aqueous suspensions of gold nanoparticles using parallel nanosecond pulsed laser.
abstract: Using 532 nm parallel nanosecond pulsed laser, the decolorization of methylene blue (MB) in aqueous suspensions of gold nanoparticles (GNPs) was studied. The effects of various experimental parameters, such as irradiation time, laser energy, and initial MB concentration on the decolorization rate were investigated. Experiments using real samples of textile dyeing wastewater were also carried out to examine the effectiveness of the method in more complex samples. From the results, the following conclusions may be drawn: (i) Under the optimum conditions (pH 7.19, 135 mJ laser energy, 4 mg/L MB concentration, and 11.6 mg/L GNP concentration), the rate of MB decolorization could reach 94% in 15 min. The decolorization follows pseudo-first-order kinetics; (ii) The amount of MB decreased rapidly during the decolorization. No intermediates of the decolorization could be detected by high-performance liquid chromatography. These observations indicate that MB was decolorized through a very rapid degradation mechanism; (iii) The rate of MB decolorization increased with the increase in laser energy (at laser energies of 0 to 135 mJ); and, (iv) The efficient decolorization of MB in real samples of textile dyeing wastewater was achieved at a decolorization rate of about 85% in 15 min.
authors.affiliation: College of Environment Science and Engineering, Tianjin University, Tianjin, China.
authors.forename: Yan P
authors.initials: YP
authors.lastname: Zong
authors.forename: Xian H
authors.initials: XH
authors.lastname: Liu
authors.forename: Xi W
authors.initials: XW
authors.lastname: Du
authors.forename: Yi R
authors.initials: YR
authors.lastname: Lu
authors.forename: Mei Y
authors.initials: MY
authors.lastname: Wang
authors.forename: Guang Y
authors.initials: GY
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D003116:Color; D004396:Coloring Agents / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007834:Lasers; D053768:Metal Nanoparticles / Q000737:chemistry*; D008751:Methylene Blue / Q000737:chemistry*; D013535:Suspensions; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D013535:Suspensions; D014874:Water Pollutants, Chemical; D006046:Gold; D008751:Methylene Blue